The present disclosure relates to metal foams, more particularly, to a dual investment method to manufacture metal foam.
Reticulated metal foams are porous, low-density solid foams that includes few, if any, intact bubbles or windows. Reticulated metal foams have a wide range of application and may be utilized in many aerospace applications.
Numerous existing manufacturing technologies for producing reticulated metal foams have been attempted, however, automated production of such reticulated structures may be rather difficult to implement as the ceramic investment often proves difficult to remove without damage to the resultant relatively delicate metallic foam structure. Further, the existing manufacturing technologies lack the capability to efficiently manufacturer relatively large sheets of metal foam as the weight of the ceramic investment is sufficient to crush and convolute the shape of the polyurethane foam precursors. This may result in castability complications, polymer burnout, and reduced dimensional tolerances.
Current standard practice for the flask investment of patterns for investment casting involves use regular geometric solids as the flask. This results in a mold with a consistent cross section that will tend to naturally cooled from the exterior surfaces inward. This inward cooling leads to an outside-inward solidification of cast metal which may result in shrinkage porosity in the last area to solidify.